Breechblock return mechanism



June 19, 1951 P. MUDESPACHER BREECH BLOCK RETURN MECHANISM warn/10R BY z Affarzze s Filed Jan. 7, 1942 av-IVA Patented June 19, 1951 ZSTATES PATENT OFFICE "BREECHBIJOCK RETURN MECHANISM Paul Miidesiaach-er, Zurich-O'erlikori, Switzerland. assignor to Verwaltungsgesellschaft der Werkzeugmaschinenfabrik Oerlikon, Zurich- Oerlikon, Switzerland "A plicationanuary 7, 194.2, serialgnmiz'asz lnswitzerland ember-23, 1940 Section 3, Public Laweso, August 8,1946 Patent expires October"23, 1960 springhave various advantages over rigidly 'locked weapons. As a result of their relatively simple menstruation, the mass locked weapons are in par- "ticular extremely robust and sure in action.

On the other hand, a disadvantage o'f the mass locked systemis that there are limits to any increase in the rate of firing. This is due to the fact that the breech block requires a certain time for its backward'andforwardmovement which, even with strong recoil springs in combination 1'5 with'a far-reaching reduction of the weight of the breech block mass, 'cannot be reduced to such anextent that veryhi'gh rates of firi'n'g can be obtained. Particularly in cases where a breech block mass which is heavy in relation to the total weight of the weapon is provided, a rate of firing of over 300 shots per minute is scarcely attainable. But even in the case of weapons with a relatively light breech block, the maximum rate of firing is about 600 shots per minute.

This firing rate could not be reached by alterations in the construction of the prior mass-locked weapons on account of the fact mentioned, viz., that the principle of mass locking sets limits to any increase in the rate of firing. Hence fundamentally new methods had to be sought to obtain rates of firing in keeping with modern requirements whilst retaining the proved system of mass or inertia locking.

The present invention solves the above mentioned problem by the fundamentally new idea in mass locked weapons of reducing the travel of the breech block, and hence the time between the individual shots, by movably mounting the barrel and the parts rigidly connected therewith. Hence, a counter movement is produced between the breech block on the one hand and the barrel on the other hand which considerably reduces the movement of the breech block.

Fundamentally, when two masses move against one another like the barrel and the breech block in accordance with the present invention, the breech block movement will be shortened in every case, irrespective of the weights of the two masses. On the other hand, by suitably dimensioning the barrel and the breech block, an optimum can be attained, possibly if the path travelled by both masses moving to and from one another is equally great. This is the case if the combined weight of the barrel and the parts rigidly fixed thereto corresponds approximately to that of the breech "block. The path to be traversed by thebijeech 'block is then rducedto a half ,which corresponds to an increase in the rate of firin'gof about*50%. In the accompanying drawings are shown, by

fway oi example, two constructional forms of the invention v In said drawing, Figs. and 2 are, respectively, horizontal and vertical sections through a firearm constructed in'accordancefwith the invention, while-Fig. 3is a view"siimlilarto Fig. 2 but showing the parts atithe-in stant of firing. The

barrel I is fixeld in the breec h casing 2 by means of a'bayori'et joint *3. In the housing 4, which is rigidly'fixed to th'e mountingare bufier springs emucerwmcn therear spring 6 acts as a buffer for the b'arrel if, in the extreme case, its

recoilmovement oversteps the normal value, while the from 'S'prii'igB acts'asabufrer for thebalirel when after the last shot and in company with the breech block, it returns to its forward rest postition under the action of the return spring Ill. The breech block recoil spring 9 is arranged directly in the breech block casing 2 and bears at its rear end against a band [6. The rear part of the breech block casing 2 slides in an enlargement of the housing 4 in which the trigger mechanism II is also arranged. The trigger levers for continuous and single-shot firing are shown at M and [5. The trigger setting takes place by rotation of a frame on which the roller of the lever I2 slides along with the movement of the barrel. The return spring I0 is arranged round the front part of the barrel, and bears on a sleeve 13 screwed on to the housing 4.

The manner of operation of the firearm shown in Figs. 1 to 3 is briefly as follows: In the stationary position shown in Figs. 1 and 2, the breech block recoil spring 9 is relieved from tension down to the pre-tension. If the firearm is cooked by drawing back the breech block I, the breech block recoil sprin is compressed. If now the trigger is set, the barrel and the breech block casing are driven rearwardly in opposition to the advancing breech block. The firing position is shown in Fig. 3, and, as can be seen, the barrel is situated in its rearmost position. At the instant of firing, the breech block 1 will be driven backwards, the recoil spring 9 will be compressed, and the barrel and breech block casing will be driven forward under the action of the previously fully tensioned return spring I0, aided by the expandin explosion gases.

During continuous firing the barrel will never completely reach its most forward position since, before it can take up this position under the ac- 3 tion of the sprin ill, the breech block will already have begun to run forward again after reaching its rearmost position under the tension of the recoil spring 9, and, therefore, the barrel will already have been driven back again by the tensioned recoil spring.

What I claim and desire to secure by Letters Patent is:

1. A massor inertia-locked automatic firearm comprising a housing, a, breech block casing movable within the housing, a barrel connected with the breech block casin to move therewith, a breech block slidable within the casing, and a recoil spring between the breech block and its casing and acting, after the expansion of the gases following the explosion of a cartridge, to cause the breech block and barrel to move toward each other into firing position, whereby the travel of the breech block is reduced.

2. A firearm according to claim 1 wherein the breech block on the one hand and the barrel and breech block casing on the other are approximately equal in weight.

3. A massor inertia-locked automatic firearm comprising a housing, a breech block casing slidthe recoil spring produces the afore-mentioned opposed movements of breech block and breech block casing.

4. A firearm according to claim 3, including 4 I buffer spring mechanism for cushioning the barrel toward the end points of it forward and rearward travel.

5. A massor inertia-locked automatic firearm comprising a housing, a breech block casing slidable within the housing, a barrel rigidly connected with the casing to slide therewith, a breech block slidable within the casing, a recoil sprin between the breech block and casing and actin to urge the breech block forwardly and the casing rearwardly, whereby the travel of the the breech block is reduced, a return spring bearing on the barrel and housing and acting to urge the barrel forwardly, and buffer spring mechanism arranged to cushion the barrel toward the end point of its forward and rearward travel.

PAUL MUDESPACHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain of 1886 Germany Nov. 24, 1919 Great Britain Aug. 30, 1939 Great Britain Feb. 6, 1940 Switzerland Jan. 5, 1942 Number Number 

